A wide variety of conveying equipment is used to stack bulk material such as gravel, coal, sand, grain, wood waste, dirt and other particulate. Such equipment often is in the form of a belt-type conveyor system, which is able to convey bulk material from a crushing and/or screening plant to create one or more stockpiles or stacks. The stockpiles may take the form of individual conical stacks but more often take the form of an array of stacks formed through the use of so-called radial stackers that can swing radially from side-to-side. Other stackers may be in the form of telescoping stackers, which may also be radial stackers and which are sometimes able to form larger and higher stacks.
Radial stackers have in recent years been designed to be portable. Portable stackers use a carriage having wheels or tracks that are typically mounted to support the power source, usually an internal combustion engine, which provides hydraulic power to the working components of the stacker. When wheeled carriages are used, the conveyor can be pulled down the highway by a tractor instead of having to be loaded onto a flat-bottomed trailer, which is normally the case with tracked carriages. In order to shorten the length and the height of the stacker, the front and/or the rear ends of the stacker are often designed to be folded over one another.
While these stacker designs have proven very popular and successful for many operations, a least one drawback exists with such designs. First, the weight of the engine is centrally disposed, and this limits the height or length of the conveyor because otherwise the front end of the stacker might become unstable and perhaps even topple over. This in turn limits the angle of extension and thus the height of the stack.
This issue has been addressed by attempts to place a box, typically filled with concrete, under the end of the conveyor belt, below the hopper. This does shift the center of gravity rearward and thereby permits the forward end of the stacker to be positioned at a sharper angle, thus increasing the height of the stacks formed thereby. However, because of the position of the box, access to the return idler pulley is restricted. Moreover, some of the material being conveyed by the belt tends to adhere to the belt and as the inverted belt reaches the rear end of the conveyor, some of that material often tends to fall onto the top of the upwardly facing, broad surface of the concrete-filled box. It is difficult to clear out this material since safety mesh often guards this underside area of the conveyor. In time, this material may pile to a height that it reaches the returning belt, and can wear or even tear the belt. This problem is exacerbated if the material freezes into a hard, abrasive mass.
Another approach, which solves the problems with the concrete-filled box below the belt is to use a pair of heavy steel plates, which may be from four to five inches thick. One of these plates is mounted to each side of the conveyor, again, below the hopper. Because the plates are not directed below the belt, and extend vertically, there is little surface on which material can collect. Also, because there are two such weights, they are somewhat easier to handle and often may be simply mounted to heavy duty, exterior hooks, rather than having to position a box below the belt. However, because the weights are made of steel, they can be expensive.